In the past, whenever an X-ray is required of a patient who is lying on a hospital bed, cooperation by the patient is necessary to elevate portions of the patient's body so that an X-ray film cassette may be inserted thereunder. This task becomes significantly more difficult or utterly impossible when the patient is immobilized by injury or anesthesia. More particularly, in the course of certain surgical procedures, it may be desirable to obtain X-rays of a fully draped and anesthetized patient to determine the degree of success of the operation so that corrections may be made promptly.
A number of X-ray apparatus have been developed to provide a solution to this problem. For example, U.S. Pat. No. 4,205,233 issued to Craig et al. on May 27, 1980 provides an X-ray table with a slidable bucky tray for carrying an X-ray film which can be moved by manual manipulation through a longitudinal opening in the table. U.S. Pat. No. 3,040,174 issued to Robin on Jun. 19, 1962 describes a device for immobilizing infants for taking X-rays which has a slidable X-ray film tray located beneath the top surface of the device. The tray may be positioned manually through several slot openings in the side of the device. U.S. Pat. 2,567,566 issued to Kizaur on Sep. 11, 1951 describes a slidable X-ray film carriage located beneath the table which may be positioned manually by grasping a handle on the carriage extending through a longitudinal slot and exerting force thereon.
Although the above-described apparatus provides for the ability to furnish an X-ray film beneath the patient, the X-ray film is movable and positionable only by manual manipulation through slots or openings alongside the table, which likely interferes with procedures being performed on the patient in an emergency situation or in the operating room. Additionally, such slots or openings are likely to be rendered inaccessible by the surgical drapes. A number of X-ray apparatus were developed in response to this concern. For example, U.S. Pat. No. 2,888,567 issued to Land on May 26, 1959 shows an X-ray tilt table which includes a film cassette carriage manually movable longitudinally beneath the table by turning a hand crank. The cassette carriage as well as the end of the table have hinged doors for loading and unloading the film cassette. However, a further need in X-ray apparatus has not been satisfactorily addressed.
In certain applications, it is necessary to position the X-ray film cassette and repeatably return the cassette to the same position with some precision. Furthermore, it may be necessary to move and reposition the X-ray film cassette relative to a prior location with some precision. U.S. Pat. No. 4,916,725 issued to Quinter et al. on Apr. 10, 1990 and U.S. Pat. No. 2,989,634 issued to Ould et al. on Jun. 20, 1961 both attempted to offer a solution to the problem of accurate X-ray film positioning. Quinter et al. shows an improved apparatus on the device taught by Ould, both providing an X-ray table with an X-ray film cassette push rod etched with graduations that can be inserted from one end of the table to move the cassette. Quinter et al. additionally provides a graduated scale along the length of the table, so that the film cassette may be moved to a second position relative to the first by looking at the displacement indicated by the graduated scale. Both devices taught by Quinter and Ould are inadequate for a number of reasons. First, by providing a scale along the length of the table, the X-ray technician must operate the push rod from a location at the end of the table and at a location beside the bed for a clear view of the scale. The technician must move between these two locations to position, adjust and readjust the X-ray film cassette. The alternative is to provide a two-person operation where one manipulates the rod and the other visually aligns the film cassette to the measurements on the scale.
Second, when a patient is fully draped or being operated on by medical personnel, it is difficult or impossible to achieve visual contact with the graduated scale for a precise positioning of the film cassette. Third, a typical operating room does not provide sufficient space at the end of the operating table for using the push rod, as the rod must be sufficiently extended horizontally to insert it under the table and to move the film cassette longitudinally. Difficulties arise especially when the film cassette is being pulled to the end of the table to be loaded or unloaded. Therefore, the Quinter and Ould devices are especially unsuitable in an operating room application where the table is under drapes and where there is not sufficient room at the end of the operating table for manipulating the push rod.
Accordingly, it is desirable to provide X-ray apparatus for accurate and repeatable positioning of an X-ray film cassette beneath a patient, especially in an operating room situation where the operating table is under drapes and space is scarce. Furthermore, it is vital that the film cassette is manipulatable and positionable without disturbance or interference with the medical personnel who are performing important medical procedures.
In a particular application, consider a replacement arthroplasty procedure for installing a trial knee prosthetic implant. It is often desirable to check the alignment of the trial knee prosthetic implant with respect to the femoral head of the hip and the ankle during the arthroplasty procedure. In addition to the problem of positioning the film under a fully draped and anesthetized patient, the special problem of taking an X-ray of an extraordinarily large area is also encountered. Typically, a standard full-length (36".times.14") X-ray film is used to obtain an X-ray image of the entire leg. However, it is not possible to obtain a full-length X-ray during surgery because of the inability or unfeasibility of positioning such a large film under the patient. Furthermore, even if a full-length X-ray film is somehow positioned under the patient during surgery, the X-ray source often cannot be positioned far enough above the patient to obtain coverage of a full-length film. There is additionally the problem that the full-length film may not be long enough to receive the image of the entire leg in a taller patient.
Therefore, it is desirable to provide a method for taking X-rays to determine the alignment of a certain body part with respect to another without having to use full-length X-ray film.